What is the central idea of the following section of the article "Need Those ZZZZZs: Young Night Owls Still Require Plenty of Sleep"?

Under construction
Just as important, burning the midnight oil can interfere with brain development when teens hit puberty, the number of long brain waves drops during non-REM (rapid eye movemen) sleep.
Neuroscientist Ian Campbell and Irwin Feinberg at the University of California, Davis, suggest the drop shows that the brain is pruning unnecasary connections between nerve cells. The brain loses some plasticity--the ability to adapt in response to injury or other big changes. But the process lets the brain mature. "it will streamline your brain-- make it more efficient adult brain," explains campbell.
In August 2014, the AAP urged high schools nationwide to delay start times to at least 8:30 a.m. Later starts can let teens get a bit more sleep when their brains really want it. Unfortunately, not all schools can or will heed that advice. And you can't easily change your body's natural circadian rhythm.